Antoine Claudet, the daguerreotypist, and his son(s) (grandson?), with scientific equipment invented by Claudet relating to photography, the 1844 focimeter, the photographometer of 1848 and the multiple plate dark slide shown in the Great Exhibition of 1851. All are posed in front of a large window with curtains.
http://en.wikipedia.org/wiki/Antoine_Claudet
http://www.getty.edu/art/collection/objects/57698/antoine-claudet-self-portrait-of-antoine-francois-jean-claudet-and-his-son-henri-posed-with-his-invention-the-focimeter-french-about-1856/
http://www.npg.org.uk/collections/search/person/mp06792/antoine-claudet
http://www.photolondon.org.uk/pages/details.asp?pid=1237
https://books.google.co.uk/books?id=Kd5cAgAAQBAJ&pg=PA538&lpg=PA538&dq=focimeter+claudet&source=bl&ots=eslT_h4BbV&sig=Fc3yIcCfs4KLMTOUj88sB_Du_0s&hl=en&sa=X&ei=E5AJVZaFHYK6ad7CgrAN&ved=0CCwQ6AEwAg#v=onepage&q=focimeter%20claudet&f=false
https://books.google.co.uk/books?id=yVFdAgAAQBAJ&pg=PA303&lpg=PA303&dq=Photographometer+claudet&source=bl&ots=bzTcs9byhZ&sig=jDENLW_S6Ygj2lPEpw5vwP6iObI&hl=en&sa=X&ei=85AJVbLSJovmaNOXgcAD&ved=0CDUQ6AEwBQ#v=onepage&q=Photographometer%20claudet&f=false